Compression packings – one of the oldest sealing techniques remains indispensable in industry today with new types of materials.
Sealing using fibre braids is one of the oldest sealing techniques and has a long tradition at Garlock – on 19 January 1886, O.J. Garlock received confirmation of his first patent, which was granted on compression packings for steam engines. Since that time, many innovative compression packing technologies have been developed at Garlock.
With the development of new types of materials and material combinations for modern industry, Garlock is meeting the increasing sealing requirements in the compression packing sector. This is where application-oriented research and the use of new designs come into play.
Today, compression packings are often replaced by dynamic ring seals such as PS-SEAL® for rotating shafts. Compression packings are always the first choice for sealing valves, as they seal them safely and reliably. New materials and configurations are currently setting standards in compression packing technology.
Compression packings can be made of many different materials, such as graphite, carbon, PTFE, aramid and synthetic fibres. Braided packings are used in various constructions and braid structures. LATTICE BRAID® is the trademarked name for the diagonal braid developed by Garlock in 1940. Each strand passes through the packing at an angle of 45° and thus contributes to the strength of the whole packing. LATTICE BRAID® is therefore a particularly homogeneous, elastic and wear-free braid. Thanks to its high flexibility, the packing remains dimensionally stable even when bent around small radii.
Besides braided packing cords, another design of compression packing is the Cup & Cone design. The conical shape of adapters and sealing rings provides high radial expansion at the inner and outer diameter resulting in good sealing. The Cup & Cone Design packing sets utilize this angular force transmission, and also the good density and friction factor of graphite sealing rings. Since the sealing rings are only compressed during installation, they adapt particularly well to the available installation space. Different angles on the adapters and sealing rings result in a high radial expansion. During compression, the upper and lower adapters set the geometry and are not compressed. This means that friction only occurs on the sealing rings resulting in low torque to turn the stem. Adjustment of the seal is not normally necessary, but is still possible in the event of volume loss.
With different Cup & Cone designs, a very wide range of applications can be covered. Style 9000-EVSP LE and style 9001 Quickset LE are Garlock compression packings in Cup & Cone design, which are the ultimate solution for environmental protection due to the reduced VOC emissions.
Highly topical: packings for Molten Salt applications in solar energy. Concentrated Solar Power (CSP) plants generate energy by heating a medium with mirrors. The heated medium can store the energy so that the power plant can convert this heat into electricity for a whole day. To make this process efficient, molten salt is often used as the medium, but this presents a sealing challenge. Depending on the system, the working temperature can be in two ranges: The lower temperature is around 420°C and the higher temperature can be up to 600°C.
Garlock packing set 1220 MS (Molten Salt) POWERPACK is designed for lower temperature applications in solar power plants up to 450°C. The packing set combines temperature resistant SYNTHEPAK® fibres with oxidation inhibitors and a THERMa-PUR® insulation spacer ring. Packing 9020 HMS (Hot Molten Salt) POWERPACK and 9021-HMS POWERPACK are designed for applications in solar power plants with higher temperatures up to 600°C. The packing design combines Cup & Cone sets with high performance valve stem packing rings and THERMa-PUR® insulation spacer rings.
Garlock compression packings offer many advantages, such as easy assembly and maintenance, excellent sealing force distribution, long service life, and fibre materials that are gentle on the shaft. Novel materials and configurations make them suitable for use in countless industries due to their high temperature and pressure resistance as well as their good chemical and physical resistance, even to abrasive media.